With the development of LED chip technology and encapsulation technology, more and more LED products have been applied to lighting field, especially white light LED of high power. Due to its high light efficiency, long service life, energy conservation and environment protection, proper light regulation and absence of polluting substances including mercury, LED lights have become the new lighting source after traditional incandescent light bulbs and fluorescent lamps.
However, current LED modules existing the following disadvantages:                1. the light emitted from the LED chip of the existing LED modules should pass air medium, which will cause interface loss, resulting in low luminous efficiency of LED chip;        2. once any moisture has entered, the LED illuminant will be damaged because of the absence of fillers between the lens group and heat sink in the existing LED modules;        3. the LED illuminants of the existing LED modules transmit the heat to the circuit board only through the bottom of the heat sink holder, that renders poorer radiation efficiency.        